Shuttle O-rings cleared for liftoff
Hot rocket gas damaged two wiper O-rings at the base of each of space shuttle Columbia's boosters during liftoff last February. NASA says the singed seals did not endanger the lives of the crew as they are not required to seal during flight. The damaged O-rings differ from those used to secure hot fuel inside the solid rocket booster, in that they are used during assembly to keep glue away from the primary, protective O-rings.
The problem manifested itself to the crew during blastoff when an indicator showed that one of the three main engines was not operating at full power. The cause was revealed after a routine examination of the solid fuel rocket boosters, upon retrieval from the ocean, and although wiper O-rings have been discovered to be singed on nine previous occasions, this was the first time the seal was scorched in two places.
Extensive analysis of the flights and test data was carried out before the Atlantis was cleared for launch on 2 1 st March by NASA managers, who concluded that the nozzle-to-case joint was robust and sturdy, and that the joint's design was safe to fly.